RESUMEN
Linear diterpenes isolated from aerial parts of Baccharis thymifolia ( 1- 3) were tested for insect growth inhibitory activity against Tenebrio molitor larvae. Compounds 4- 16 were prepared by various chemical transformations. The diterpenes 6,10-( E,E)-thymifodioic acid ( 1), the butenolide 3, and the derivatives 4, 11, and 14 produced developmental deficiencies in assays using topical application on fifth instar larvae of T. molitor. Compound 3 is a new natural product.
Asunto(s)
Baccharis/química , Diterpenos/aislamiento & purificación , Diterpenos/farmacología , Insecticidas/aislamiento & purificación , Insecticidas/farmacología , Plantas Medicinales/química , Animales , Argentina , Diterpenos/química , Insecticidas/química , Larva/efectos de los fármacos , Estructura Molecular , Tenebrio/efectos de los fármacosRESUMEN
In order to establish structure-activity relationships, nine neo-clerodane diterpenes isolated from the acetone extract of aerial parts of Baccharis flabellata Hook & Arn var. fabellata were assayed for antifeedant activity against Tribolium castaneum (Coleoptera: Tenebrionidae). Compounds exhibiting maximal antifeedant activities showed an alpha,beta-unsaturated carbonyl group on the decalin portion and a furan ring at the side chain. Stereoelectronic studies indicate that the distance between the furan heteroatom and the more electrophilic carbon of the decaline moiety, as well as the electrostatic charge on that atom, were important features for antifeedant activity. Compounds possesing an alpha,beta,gamma,delta-unsaturated carbonyl group or an acetoxyl group at C-2, were inactive. Theoretical calculations were performed in order to find some structure-activity relationships.
Asunto(s)
Baccharis/química , Diterpenos de Tipo Clerodano/química , Diterpenos de Tipo Clerodano/farmacología , Tribolium/efectos de los fármacos , Animales , Diterpenos de Tipo Clerodano/aislamiento & purificación , Conducta Alimentaria/efectos de los fármacos , Conformación Molecular , Resonancia Magnética Nuclear Biomolecular , Rotación Óptica , Espectrometría de Masa por Ionización de Electrospray , Espectrofotometría Ultravioleta , Espectroscopía Infrarroja por Transformada de Fourier , Relación Estructura-Actividad , Tribolium/fisiologíaRESUMEN
Allelochemical effects were observed when Tribolium castaneum (Herbst) adults were treated with Baccharis salicifolia (Ruiz & Pavon) Pers essential oil. The main biological activities were toxicity and repellence. Terpenes present in the essential oil were identified by GC-MS, and some authentic samples were tested to assess their activity individually. The most acutely toxic compounds after 3 days were beta-pinene and pulegone. Most of the monoterpenes elicited symptoms indicative of neurotoxicity. The most repellent compound was alpha-terpineol. Toxic and repellent effects of chemical derivatives of the major sesquiterpene present in B salicifolia essential oil, as well as a series of monoterpenes, were evaluated in order to investigate structure-activity relationships. The reduced derivatives of the monoterpenes and sesquiterpenes were more repellent that their carbonyl analogues. In addition, unsaturation in the germacrane skeleton enhanced repellent activity.
Asunto(s)
Baccharis/química , Repelentes de Insectos , Insecticidas , Aceites Volátiles/química , Aceites Volátiles/farmacología , Tribolium/fisiología , Animales , Estructura Molecular , Monoterpenos/química , Monoterpenos/farmacología , Sesquiterpenos/química , Sesquiterpenos/farmacologíaRESUMEN
To validate the potential as added-value resources of Asteraceae and Labiatae species of Argentinean semi-arid lands, we have selected 13 of their major terpenoids belonging to several chemical classes and tested their insect antifeedant and toxic activity on the herbivorous insects Spodoptera littoralis and Leptinotarsa decemlineata. The antifeedant effects of the test compounds were structure- and species-dependent. The most active antifeedant to L. decemlineata was the eudesmane sesquiterpene gamma-costic acid (13), followed by the labdane diterpene 2alpha,3alpha-dihydroxycativic acid (8), the clerodane diterpenes 6-acetylteucjaponin B (5), bacchotricuneatin A (1), bartemidiolide (7), butanolide (4), and the sesquiterpenes ilicic acid (11) and tessaric acid (10) (eudesmane and eremophilane type, respectively). S. littoralis was only affected by the clerodanes and showed the strongest response to salviarin (3) and 5, followed by hawtriwaic acid (6) and 12-epi-bacchotricuneatin A (2). Orally injected S. littoralis larvae were negatively affected by 5. Most of the diterpenes had selective cytotoxic effects to insect-derived Sf9 cells with the clerodane 1 being the most active, followed by the eudesmane costic acid (12), the only cytotoxic sesquiterpene. None of these compounds was cytotoxic to mammalian CHO cells.
Asunto(s)
Asteraceae/química , Lamiaceae/química , Sesquiterpenos/química , Terpenos/química , Alimentación Animal , Animales , Antiinfecciosos , Argentina , Asteraceae/clasificación , Asteraceae/parasitología , Clima Desértico , Insectos/patogenicidad , Lamiaceae/clasificación , Lamiaceae/parasitología , Enfermedades de las Plantas/parasitología , Sesquiterpenos/toxicidad , Spodoptera/efectos de los fármacos , Spodoptera/patogenicidad , Terpenos/toxicidadRESUMEN
Growth inhibitory activities and nutritional indices of catalpol (1), 8-O-acetylharpagide (2), and harpagide (3) were determinated in larvae and adults of Tribolium castaneum, respectively. Compound 1 produced a series of allelochemical effects probably related with the DNA synthesis. This iridoid possessed the highest inhibitory activity against DNA polymerase. Molecular orbital calculations suggest that a pi-pi charge transfer recognition model could explain the action of iridioids toward nucleic acid synthesis.
Asunto(s)
Inhibidores Enzimáticos/aislamiento & purificación , Inhibidores Enzimáticos/farmacología , Glucósidos/aislamiento & purificación , Glucósidos/farmacología , Control de Insectos , Iridoides/aislamiento & purificación , Iridoides/farmacología , Inhibidores de la Síntesis del Ácido Nucleico , Inhibidores de la Síntesis del Ácido Nucleico/aislamiento & purificación , Inhibidores de la Síntesis del Ácido Nucleico/farmacología , Piranos/aislamiento & purificación , Piranos/farmacología , Tribolium/efectos de los fármacos , Animales , Inhibidores Enzimáticos/química , Glucósidos/química , Glucósidos Iridoides , Glicósidos Iridoides , Iridoides/química , Larva/efectos de los fármacos , Modelos Moleculares , Estructura Molecular , Inhibidores de la Síntesis del Ácido Nucleico/química , Piranos/químicaRESUMEN
Eight eudesmane and eremophilane sesquiterpenes administered to Tribolium castaneum larvae caused different allelochemical effects. Topical application of 3-oxo-gamma-costic acid produced the greatest lengthening in the duration of the pupal stage. Morphological deformities were found, specifically when ilicic, costic, and gamma-costic acids and costic aldehyde were used. Ilicic acid exhibited the major toxicity 72 hr following topical application. All compounds were significantly toxic at the end point of the experiment (60 days). Treated surface toxicity was lower than when topical assays were carried out. Responses to tessaric acid in choice bioassays had the highest attractive effect. Maximum repellency was caused by the 3-oxo-gamma-costic acid. However, experimental series carried out using gamma-costic acid, eremophilan-1(10),2,11(13)-trien-12-oic acid, costic aldehyde, and ilicic aldehyde showed no clear response.
Asunto(s)
Movimiento , Naftalenos/farmacología , Sesquiterpenos de Eudesmano , Sesquiterpenos/farmacología , Tribolium , Administración Tópica , Animales , Bioensayo , Células Quimiorreceptoras , Larva , Sesquiterpenos PolicíclicosRESUMEN
Two clerodane-type diterpene glycosides esters, which were studied as peracetyl derivatives, together with the known diterpene marrubiagenine, were isolated from the aerial part of Baccharis sagittalis (Less). Their structures were established by spectroscopic methods. Antifeedant activity toward Tenebrio molitor larvae of the isolated compounds along with six other diterpenes was evaluated and some structure-antifeedant bioactivity relationships are reported.